scholarly journals Influence of an upper layer liquid on the phenomena and cavity formation associated with the entry of solid spheres into a stratified two-layer system of immiscible liquids

2018 ◽  
Vol 30 (6) ◽  
pp. 064104 ◽  
Author(s):  
Benedict C.-W. Tan ◽  
Peter J. Thomas
Keyword(s):  
Cavity Formation ◽  
Layer System ◽  
Immiscible Liquids ◽  
Solid Spheres

Cavity formation in the wake of falling spheres submerging into a stratified two-layer system of immiscible liquids

2016 ◽  
Vol 790 ◽  
pp. 33-56 ◽  
Author(s):  
Benedict C.-W. Tan ◽  
J. H. A. Vlaskamp ◽  
P. Denissenko ◽  
P. J. Thomas
Keyword(s):  
Data Analysis ◽  
Cavity Formation ◽  
Layer System ◽  
Rigid Spheres ◽  
Immiscible Liquids ◽  
Homogeneous Liquid ◽  
Falling Spheres ◽  
Ripple Patterns ◽  
Dimensional Instability ◽  
Layer Coating

We experimentally study the cavities forming in the wake of rigid spheres when submerging into a stratified, two-layer system of immiscible, quiescent liquids comprising a thin layer of oil above a deep pool of water. The results obtained for our two-layer system are compared with data from the literature for the corresponding type of cavities formed when spheres enter a homogeneous liquid that is not covered by an oil layer. The discussion and the data analysis reveal that the oil coating acquired by the spheres while propagating through the thin oil layer, before entering the pool of water underneath, substantially affects qualitative and quantitative aspects of the dynamics associated with the cavity formation. In particular, we observe the formation of a ripple-like pattern on the cavity walls which is not known to exist when spheres enter a homogeneous liquid. The data analysis suggests that the ripple patterns form as a consequence of a two-dimensional instability arising due to the shear between the oil layer coating the spheres and the ambient water.

Steady Rayleigh–Be´nard Convection in a Two-Layer System of Immiscible Liquids

1996 ◽  
Vol 118 (2) ◽  
pp. 366-373 ◽  
Author(s):  
A. Prakash ◽  
J. N. Koster
Keyword(s):  
Numerical Simulations ◽  
Thermal Convection ◽  
Reasonable Agreement ◽  
Two Dimensional ◽  
Thermal Coupling ◽  
Layer System ◽  
Immiscible Liquids ◽  
Mechanical Coupling ◽  
Buoyancy Forces ◽  
Coupling Mode

Two-dimensional thermal convection in a system of two immiscible liquids heated from below is studied experimentally and numerically. Convection in the two-layer system is characterized by two distinct coupling modes between the layers. They are mechanical coupling and thermal coupling. These two coupling modes are visualized experimentally and found to be in reasonable agreement with numerical simulations. When buoyancy forces in both layers are of similar strength, thermal coupling is preferred. The mechanical coupling mode dominates when the buoyancy forces are very different in both layers.

scholarly journals Velocity Profiles for Flow of Omani Crude Oils and Other Liquids

2014 ◽  
Vol 19 (1) ◽  
pp. 87
Author(s):  
Sayyadul Arafin ◽  
S. M. Mujibur Rahman
Keyword(s):  
Differential Equation ◽  
Laminar Flow ◽  
Velocity Profiles ◽  
Momentum Balance ◽  
Crude Oils ◽  
Distinctive Pattern ◽  
Layer System ◽  
Immiscible Liquids ◽  
Momentum Balance Equation ◽  
Liquid Systems

Velocity profiles of Newtonian immiscible liquids undergoing laminar flow between two horizontal plates under pressure gradient are investigated using a momentum balance equation. The differential equation describing the flow has been solved and equations for the velocity profiles of a two-layer and three-layer liquid systems are presented. As examples, we show flow patterns of two-layer water-crude oil system and three-layer system involving water, tetrachloromethane, xylene, cyclopentane and hexane. A distinctive pattern is noticeable between the velocity profiles of heavy (API 19.19) and light (API 40.89) Omani crude oils.  

scholarly journals Frozen wave simulation by the lattice Boltzmann method

2021 ◽  
pp. 59-68
Author(s):  
I. V. Volodin ◽  
◽  
A. A. Alabuzhev ◽  
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Wave Number ◽  
Phase System ◽  
Layer System ◽  
Two Phase ◽  
Immiscible Liquids ◽  
Two Fluids ◽  
Linear Vibrations ◽  
Boltzmann Method

The dynamics of two-layer system of immiscible liquids under the action of horizontal linear vibrations in the field of gravity was investigated. The numerical simulation was carried out by the lattice Boltzmann method (LBM) with model D2Q9. For the first time LBM was used to achieve the appearance of frozen wave (quasi-stationary relief) at the interface of two fluids. There are two types of boundary conditions for the sidewalls: a periodic condition for comparison with analytical results and no-slip condition for comparison with experiments. Various computational domains were considered. Both cases with the same viscosities of both phases and different viscosity ratios were studied. HCZ model was used to describe two-phase system and the interface of two liquids. The presence of a frozen wave on the interface of liquids was found. The dependence of liquids viscosity on the relief was studied. The obtained critical wave number coincides well with the theoretically predicted value for liquids with the equal viscosity and vanishing viscosity. The results of numerical calculations show a weak viscosity effect for a more viscous lower liquid. However, the destabilizing effect of viscosity is more significant for a more viscous upper liquid.

scholarly journals Numerical Analysis of Density-Driven Reactive Flows in Hele-Shaw Cell Geometry

2020 ◽  
Vol 10 (2) ◽  
pp. 5434-5440
Author(s):  
S. Bekkouche ◽  
M. Kadja
Keyword(s):  
Lower Layer ◽  
Immiscible Fluids ◽  
The Finite Element Method ◽  
Cell Geometry ◽  
Concentration Gradients ◽  
Layer System ◽  
Immiscible Liquids ◽  
Acid And Base ◽  
The Mathematical Model ◽  
Hele Shaw Cell

In this paper, a two-dimensional numerical simulation of the unsteady state of a two non-isothermal immiscible liquids layer system filling a reactor formed by two closely spaced parallel glass sheets, which is called an Hele-Shaw cell, vertically oriented, with an expected neutralization reaction between an acid and a base in the lower layer, under the action of gravity, is studied. Attention is given on the general behavior of the complete temporal pattern evolution (velocity, temperature, and concentration profiles) and the identification of the exothermic reaction’s role in giving birth to chemo-hydrodynamic patterns that occur because of concentration gradients. The effects of gravity and changes in initial acid and base concentrations on the formed patterns were studied. The mathematical model governing the phenomenon was solved numerically by the CFD software package COMSOL Multiphysics, with the finite element method and a comparison with the experimental data was made. The results show that this numerical tool is promising for the understanding of the reactive instabilities happening when two immiscible fluids come into contact.

A TEM study of the effect of oxygen on nanocavity formation and precipitation in rapid - solidified Fe-16Ni-9Cr stainless steels

1994 ◽  
Vol 52 ◽  
pp. 700-701
Author(s):  
S. Wisutmethangoon ◽  
T. F. Kelly ◽  
J.E. Flinn
Keyword(s):  
Stainless Steels ◽  
High Mobility ◽  
Hot Extrusion ◽  
Extrusion Ratio ◽  
Gas Atomization ◽  
Cavity Formation ◽  
Nucleation Sites ◽  
Heat Treated ◽  
Different Types ◽  
Effect Of Oxygen

Vacancies are introduced into the crystal phase during quenching of rapid solidified materials. Cavity formation occurs because of the coalescence of the vacancies into a cluster. However, because of the high mobility of vacancies at high temperature, most of them will diffuse back into the liquid phase, and some will be lost to defects such as dislocations. Oxygen is known to stabilize cavities by decreasing the surface energy through a chemisorption process. These stabilized cavities, furthermore, act as effective nucleation sites for precipitates to form during aging. Four different types of powders with different oxygen contents were prepared by gas atomization processing. The atomized powders were then consolidated by hot extrusion at 900 °C with an extrusion ratio 10,5:1. After consolidation, specimens were heat treated at 1000 °C for 1 hr followed by water quenching. Finally, the specimens were aged at 600 °C for about 800 hrs. TEM samples were prepared from the gripends of tensile specimens of both unaged and aged alloys.

“Cavity” formation in superplastically deformed aluminium alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 958-959
Author(s):  
A. Cziráki ◽  
E. Ková-csetényi ◽  
T. Torma ◽  
T. Turmezey
Keyword(s):  
Grain Boundaries ◽  
Aluminium Alloys ◽  
Superplastic Deformation ◽  
Volume Fraction ◽  
Superplastic Forming ◽  
Polished Surface ◽  
Cavity Formation ◽  
Stress Concentrations ◽  
Electron Microscopic ◽  
Commercial Aluminium

It is known that the formation of cavities during superplastic deformation can be correlated with the development of stress concentrations at irregularities along grain boundaries such as particles, ledges and triple points. In commercial aluminium alloys Al-Fe-Si particles or other coarse constituents may play an important role in cavity formation.Cavity formation during superplastic deformation was studied by optical metallography and transmission scanning electron microscopic investigations on Al-Mg-Si and Al-Mg-Mn alloys. The structure of particles was characterized by selected area diffraction and X-ray micro analysis. The volume fraction of “voids” was determined on mechanically polished surface.It was found by electron microscopy that strongly deformed regions are formed during superplastic forming at grain boundaries and around coarse particles.According to electron diffraction measurements these areas consist of small micro crystallized regions. See Fig.l.Comparing the volume fraction and morphology of cavities found by optical microscopy a good correlation was established between that of micro crystalline regions.

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